Inorganic Chemistry: s-, p- and d-Block Elements
What this domain tests
This domain tests descriptive and rationalised inorganic chemistry: trends in the s-block, the anomalous behaviour of the first member of each p-block group, the inert pair effect, and the characteristic properties of transition metals - variable oxidation states, colour, complex formation, magnetism and catalysis.
Core rules
- s-Block: reactivity with water increases down Group 1 and Group 2. Oxide basicity increases down the group; beryllium oxide is amphoteric. Solubility of Group 2 sulfates decreases down the group (lattice enthalpy falls faster than hydration enthalpy), while hydroxide solubility increases.
- Diagonal relationships: Li–Mg and Be–Al share similar chemistry, especially amphoteric hydroxides and carbonate decomposition.
- p-Block: the inert pair effect stabilises the (n−2) oxidation state for Tl, Pb and Bi, so Pb²⁺ and Bi³⁺ dominate over Pb⁴⁺ and Bi⁵⁺. Halogens become weaker oxidising agents down the group.
- d-Block: variable oxidation states arise from similar 3d and 4s energies; colour comes from d–d transitions within a ligand-field-split d subshell; Mn(VII) as MnO₄⁻ and Cr(VI) as Cr₂O₇²⁻ are strong oxidisers in acid.
Worked example
Calculate the spin-only magnetic moment of a high-spin Fe³⁺ ion. Fe³⁺ is [Ar]3d⁵; high spin means five unpaired electrons, n = 5. μ = √(n(n+2)) = √35 = 5.92 Bohr magnetons. If the same ion were low spin (one unpaired electron), μ would be √3 = 1.73 BM, so a magnetic measurement distinguishes the two cases.
Traps that cost marks
- Cu⁺ (d¹⁰) is colourless and diamagnetic, unlike Cu²⁺ (d⁹).
- Zn²⁺ is d¹⁰, so its complexes are colourless and not transition-metal-like in colour or magnetism.
- Assuming flame-test colours identify all metals - lithium crimson, sodium yellow, potassium lilac, calcium brick-red, barium apple-green, but transition metals do not give clean flame tests.